[PATCH v2] lib: sbi: Add option to select boot hart

[Anup Patel]

On Fri, Dec 2, 2022 at 12:10 PM Wei Liang Lim
<weiliang.lim at starfivetech.com> wrote:
>
> In certain scenario, user needs to select a particular hart ID as the boot hart. This option provide the flexibility for user to select the preferred boot hart.
>
> Signed-off-by: Wei Liang Lim <weiliang.lim at starfivetech.com>
> Reviewed-by: Chee Hong Ang <cheehong.ang at starfivetech.com>
> Reviewed-by: Jun Liang Tan <junliang.tan at starfivetech.com>
> ---
>  firmware/objects.mk | 4 ++++
>  lib/sbi/sbi_init.c  | 6 ++++++
>  2 files changed, 10 insertions(+)
>
> diff --git a/firmware/objects.mk b/firmware/objects.mk
> index a1704c4..2b41718 100644
> --- a/firmware/objects.mk
> +++ b/firmware/objects.mk
> @@ -28,6 +28,10 @@ ifdef FW_TEXT_START
>  firmware-genflags-y += -DFW_TEXT_START=$(FW_TEXT_START)
>  endif
>
> +ifdef FW_BOOT_HART_ID
> +firmware-genflags-y += -DFW_BOOT_HART_ID=$(FW_BOOT_HART_ID)
> +endif
> +
>  ifdef FW_FDT_PATH
>  firmware-genflags-y += -DFW_FDT_PATH=\"$(FW_FDT_PATH)\"
>  ifdef FW_FDT_PADDING
> diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
> index a8500e5..28698f1 100644
> --- a/lib/sbi/sbi_init.c
> +++ b/lib/sbi/sbi_init.c
> @@ -447,7 +447,9 @@ static void __noreturn init_warmboot(struct sbi_scratch *scratch, u32 hartid)
>                              scratch->next_mode, FALSE);
>  }
>
> +#ifndef FW_BOOT_HART_ID
>  static atomic_t coldboot_lottery = ATOMIC_INITIALIZER(0);
> +#endif
>
>  /**
>   * Initialize OpenSBI library for current HART and jump to next
> @@ -498,7 +500,11 @@ void __noreturn sbi_init(struct sbi_scratch *scratch)
>          * HARTs which satisfy above condition.
>          */
>
> +#ifdef FW_BOOT_HART_ID
> +       if (next_mode_supported && hartid == FW_BOOT_HART_ID)
> +#else

This breaks the CPU hotplug for boot HART.

In other words, the boot HART will now always take coldboot path when
it is stopped (sbi_hsm_hart_stop()) and started (sbi_hsm_hart_start())
at runtime.

>         if (next_mode_supported && atomic_xchg(&coldboot_lottery, 1) == 0)
> +#endif
>                 coldboot = TRUE;
>
>         /*
> --
> 2.25.1
>
>
> --
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Regards,
Anup